Cereals, such as barley, wheat, rye, corn, oats, rice, millet triticale, and sorghum, are used for the production of beverages. In most cases, they have been subjected to a malting process to take advantage of their increased enzymatic potential.
In traditional malting processes, the moisture content of cereals is raised either by immersion(s) and/or spraying(s), and the resulting high-moisture content cereal is allowed to germinate. After reaching the proper physiological condition, it is preferably submitted to (a) drying step(s). In what follows, the term steeping refers to the increase in moisture level, while the term germination is used in the way it is in plant physiology. The drying operations are referred to as kilning and the term malting involves all operations needed to convert barley (or other cereals) to barley malts (or other cereal malts).
The quality of the malt obtained is, to a large extent, determined by the presence of plant endogenous enzymes generated during the melting process. For instance, with cereals like barley used as a raw material for the malt production, the variety, the composition of the microbial flora and the environmental factors, such as agricultural practice, influence the quality of the malt. During cultivation and storage, cereals are contaminated with bacteria and fungi. In the malting plant, neither the air, the water, nor the equipment are sterile, and the conditions of humidity, pH and temperature favor the growth of the microbial populations. To improve the quality of malted cereals, such as barley, enzymes have been added to the malted cereal.
The variable cereal quality and the lack of means to make up for deficiencies during the malting process result in variability in malt quality and enzymatic activity. In many instances, this has to do with an imbalance of specific enzymatic potential and insufficient cell wall degradation. Apart from this, problems with microbial safety can occur. As a consequence of the defects in malt, quality problems occur in the production of beer, such as a poor filtration of the wort.